Method of manufacturing radially corrugated disks



May 3141-, 193550 4 J. A. SPENCER Q fl fi METHOD OF MANUFACTURING RADIALLY CORRUGATED DISKS Original Filed June 26, 1930 2 Sheets-Sheet l May 14, 1935. J. A. SPENCER METHQD OF MANUFACTURING RADIALLY CORRUGATED DISKS 2 Sheets-Sheet 2 Original Filed June 26, 1939 FIG.8.

FIGJO.

Patented May 14, 1935 METHOD OF MANUFACTURING BADIALLY CORRUGATED DISKS John A. Spencer, Newtonville, Mass., assignor, by

mesne assignments, to General Plate Company,

Attleboro, Mass., chusetts corporation of Massa- Original application June 26, 1930, Serial No. 463,961. Patent No. 1,895,590, dated January 31, 1933. Divided and this application January 26, 1933, Serial No. 653,701

3 Claims.

This invention relates to methods of manufacturing radially corrugated disks, and with regard to certain more specific features, to methods adapted to commence with uncorrugated blanks. This application is a division of my Patent No. 1,895,590, granted January 31, 1933, upon an application, Serial No. 463,961, filed June 26, 1930, for Snap-acting devices.

Among the several objects of the invention may be noted the provision of a method of manufacturing radially corrugated disks which commences with uncorrugated blanks of either resilient ordinary metal or composite thermostatic metal" (such as bimetal), and produces snapacting disks which are thermostatically sensitive, if composite metal has been used; a method of the class described which achieves the desired ultimate conformation without in the process subjecting the blanks to any undue localized stresses which might impair theefliciency of the resulting article; and the provision of a method of the class described which is simple and economical in operation, requiring but a minimum of specialized machinery. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, and steps and sequence of steps, which will be exemplified in the method hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which are illustrated one or more of various possible embodiments of the invention,

Fig. 1 is a plan view ofone form of blank utilized in the present method;

Fig. 2 is a plan view of an alternative form of blank;

Fig. 3 is a perspective view illustrating a first operation on a Fig. 1 type blank;

Fig. 4 is a front elevation of a roller used in the step illustrated by Fig. 3;

Fig. 5 is a back elevation of the roller shown in F18. 4;

Fig. 6 is an elevation illustrating a first operation on a Fig. 2 type of blank;

Fig. 7 is a side elevation of the roller arrangement used in the step illustrated in Fig. 6;

Figs. 8, 9, and 10 illustrate successive steps applied to either of the types of blanks shown, after the first operation has been performed thereon; and,

Fig. 11 is a top plan view of a finished, radially corrugated disk.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

As disclosed in my Patent No. 1,895,590, of which this application is a division, radially corrugated disks having a slight initial conical conformation, when made of suitable material, are useful as snap-acting elements. If the material is resilient sheet metal, the disk constitutes a valuable over-centering element; while if the material is composite thermostatic metal (such as bimetal) formed of a plurality of united metallic layers having different coefiicients of thermal expansion, the disk is a valuable self-actuating, snap-acting thermostatic unit. The present application is not concerned with the actions and reactions of these disks per se, which are adequately discussed in said patent, but in a preferred method (or methods) of manufacturing the same. The method used, particularly if the disks are thermostatic ones, needs to be such that no excessive localized stresses are produced in any one region of the disk, otherwise the temperature response characteristics of the disk might be seriously impaired. To a lesser extent, the same requirement is imposed upon the manufacture of the non-thermostatic disks, as localized stresses in such disk mean early failure, in operation, of that portion of the disk unduly strained, and 'thus shorter life of the disks taken on the average.

The method which I have found to be most advantageous comprises initially corrugating blanks with a roller system, and then pressing the corrugated blanks into final conformation in a series of die-press steps. In this manner, no great stress is introduced into any one part of the disk at any time, but rather, the stresses are more equally distributed through the whole disk from step to step, and the finished article is thus free of any excessive localized stresses.

Referring now more particularly to the drawings, Figs. 1 and 2 illustrate blanks typical of the types I use for the manufacture of the disks in question. Fig. 1, at numeral I, shows a fiat annulus. Fig. 2, at numeral 2 shows a short cylindrical section, which may be cut from a (preferably seamless) tube or pipe. Economically speaking, the cylindrical blank 2 is more advantageous than the annular blank I, as there is less waste in cutting the blank from its stock. The metal stock from which these blanks are cut comprises either springy, resilient sheet metal such as thin steel or spring brass, in Case the ultimate disk isto be non-thermostatic, or any suitable form of composite thermostatic metal (such as that shown in Marshall Patent 1,481,021, Marshall Patent 1,700,173, or Bush Patent 1,870,235) in case the ultimate disk is to be thermostatic. So far as the present invention is concerned, it is inconsequential whether the blank is for a non-thermostatic or a thermostatic disk.

In their initial steps, the blanks I and 2 are subjected to somewhat different operations, the purpose of which is to corrugate the blank in the desired manner and, at-the same time, shape it into either a cylindrical form or a conical form in which the apex angle of the cone is so small that it is nearly a cylinder.

The fiat annular blank I is passed through a pair of corrugating rollers 3 (see Figs. 3). The rollers 3 resemble bevel gears in appearance, but the shape of their teeth is preferably not like that of the usual bevel gears. As shown in Figs.

4 and 5, the teeth I of the rollers 3 taper in width fromfront to back, being narrowest in the front (or smallest diameter) region, and broadest in the back (or greatest diameter) region. The teeth of the two rollers 3 of course mesh, so that the one may drive the other. The shaping of the teeth 4, coupled with the bevel of the rollers 3, forms the fiat blank'into a cylindrical shape which tends to be slightly conical, as illustrated, at the same time that it is corrugated. In operation, the rollers are separated (suitable means for this being provided) and the blank inserted therebetween, in such manner that the meshing teeth of the two rollers will occupy radial positions on the annulus blank. After forcing the rollers together, theyare rotated and the blank is guided to maintain the original relationship (teeth radial to the annulus), while the rollers corrugate and simultaneously shape the blank. The shape of the teeth I is previously calculated so that the corrugations on the blank come out without any in the manner shown inFigs. 6 and 7. In these figures, numeral 5 indicates a pair of toothed, meshing rollers which resemble pinions in construction. The teeth 6 of the rollers I are parallel. In operation, the rollers B are separated, the blank 2 introduced therebetween in such manner that the elements of the cylinder constituting the blank are parallel tothe teeth 6,

the rollers 5 are again forced together and then" rotated. As previously, the pitch and dimensions of the teeth 8 are established such that there is no overlapping of the resulting corm- Eations in the blank 2. After one or more rotations of the blank 2, the rollers are separated and the now completely corrugated, and cylindrical blank is removed.

Since the subsequent steps are substantially identical for either original type of blank, the numeral 1 is used in the remaining figures to indicate such blanks after their first operation has been finished. That is, numeral 1 indicates the blank (either of the Fig. 1 or the Fig. 2 type) after its initial working and after commencement of the next operation to be described.

Theblank I is placed in a die 8 (Fig. 8) which has a circular depression or counterbore 9 therein. The depression 9 is relatively shallow, as it constitutes more a stop or movement limiting means than an actual shaping means. A second die Ill is now brought down on the blank 1. The die It! includes a frusto-conical depression ll located centrally therein. The walls of the depression I I are preferably slanting at only a relatively slightly greater angle than the'sides of the blank I. The die l0 automatically centralizes the blank I therein. The die III is now driven downwardly against the blank I. The effect of this is to make the blank I more conical (the apex angle becoming less acute) through a simultaneous stretching of the outer peripheral regions of the corrugations and compression of the inner peripheral regions of the corrugations. This continues until the slope of the blank sides is the same as that of the walls of the depression ii. Usually by the time this equivalency of slope is obtained (and with the first die) the lower end of the blank, and hence the base of the cone, has expanded (see Fig. 9) until it reaches the sides of the circular depression 9 in die 8. The circular depression, from this time forth, positively bars further expansion at the periphery of the blank and thus forces all additional shaping to take place by compression of the corrugations at the inner peripheral region. By this means are the disks held to a uniform size.

The die I0 is now removed and replaced by a die I2 having a similar conical depression l3, which depression has walls at a greater slope than those of the die It. The effect hereby produced is to further flatten the blank, this time entirely by compressing and further increasing the amplitude of the central portion of the corrugations.

Finally, the die I! is removed and replaced by a simple fiat-surface die H, which is pressed down upon the now relatively narrow apex of the conical blank to bring said blank to its final shape, which depends upon how great a throw of the snap-acting element is desired.

The die pressing illustrated in Figs. 8, 9, and 10 may be done in any number of steps suitable to the disk being formed and the shaping characteristics of the metal of the blank. The number shown (three: two conical-depression dies ll time I2 andone flat die H) has been found to give excellent results without introducing substantial localized stresses in the resultant disk.

Fig. 11 illustrates acompleted disk, formed in accordance with the present invention. It will be seen that its corrugations I! are positioned in the desired radial conformation, and it will be apparent that it has the desired slightly conical conformation.

It will be seen that the present invention comprises taking a blank and corrugating it in such a manner that it comes out a corrugated cylinder or nearly a cylinder, and thereafter so pressing the blank that the corrugations at one end of the cylinder are slowly compressed, while the corrugations at the other end of the cylinder are stretched or held in shape, until the blank as a whole assumes a disk-like appearance. At no time during this sequence of events is there lo-' As many changes could be made in carrying out the above constructions and processes without departing from the scope of the invention, it is intended that all matter contained in the above a seamless blank in the form of a flat annulus,

corrugating said blank with rollers in such manner that it assumes a substantially cylindrical .coniormation wherein the individual corrugations are 01' rounded contour, and compressing the corrugations at one end of the blank inwardly until the blank assumes a disk conformation in which the central portion is slightly displaced from the peripheral portion.

2. The method of manufacturing radially corrugated snap-acting disks which comprises preparing an endless blank, corrugating said blank and imparting to the individual corrugations a rounded contour} compressing the corrugations at one edge of the blank, while at the same time expanding the corrugations at the other edge of the blank, thereby imparting an approximately disk shape to the blank, and leaving the central portion of the disk shape slightly displaced from the peripheral portion.

3. The method of manufacturing radially corrugated snap-acting disks which comprises preparing an endless blank, corrugating said blank.

and imparting to the individual corrugations a rounded contour, compressing the corrugations at one edge of the blank, while at the same time expanding the corrugations at the other edge of the blank, and. thereafter continuing the compression of corrugations at the respective edge of the blank, while discontinuing the expansion of the corrugations at the other edge 01' the blank, thereby imparting an approximately disk shape to the blank, and leaving the central portion of the disk shape slightly displaced from the peripheral portion.

JOHN A. SPENCER. 

